The move paves the way for the former politician, once on track for a top leadership post, to be tried in criminal court.

BEIJING — Purged Chinese politician Bo Xilai has been expelled from the legislature in a preliminary move that will allow him to be tried in criminal court on charges of corruption and covering up his wife's role in a bizarre murder plot.

Although widely anticipated, the expulsion adds to the political turmoil in the run-up to next month's Communist Party congress, when a new leadership is to be formally anointed. Bo's supporters — mostly neo-Maoists who believe that economic reforms have gone too far — think his prosecution is politically motivated by rivals in the leadership.

The state-run news agency reported in a brief dispatch Friday morning that the National People's Congress, China's equivalent of a legislature, "announced the termination of Bo Xilai's post as the NPC deputy."

Under Chinese law, a legislator has immunity from criminal prosecution. Bo was fired from his post as Communist Party secretary in Chongqing in March after it was revealed that his wife was suspected of poisoning a British business consultant, Neil Heywood.

Bo, 63, has also been expelled from the 25-member Politburo and the Communist Party, making Friday's action something of a technicality.

Li Xiaolin, a Beijing lawyer involved with the defense, said Friday that he did not believe a trial could take place before the Nov. 8 start of the 18th party congress. Li said he had been hired by Bo's mother-in-law as part of the defense team but had not yet been able to meet with Bo.

"We hope if a trial proceeds we will have the opportunity," Li said.

Other Bo supporters expressed doubts about whether Bo would get a fair trial. A petition has been circulating in recent days among leftist intellectuals, as well as human rights advocates who are politically opposed to Bo's views, demanding that a public trial that follows due process of law be held. Only brief snippets of the August trial of Bo's wife, Gu Kailai, were shown on television, and all but handpicked observers were excluded from the courtroom.

"If the government is confident in its constitution and the political system, it should allow Bo Xilai the opportunity to defend himself," said Sima Nan, a leftist political commentator. He noted that the 1980-81 trial of Jiang Qing, Mao Tse-tung's wife and the main figure in the Gang of Four charged with treason after the Cultural Revolution, was televised in full.

Bo, the son of one of Mao's closest comrades, was considered a rival to Xi Jinping, the vice president who is to succeed President Hu Jintao. Until this spring, Bo had been a leading contender in the next generation of leadership, and he remains a hero to many Chinese nostalgic about communism as it existed before China's reform and opening. In Chongqing, where he served until March, he spearheaded a revival of dancing and singing of revolutionary songs and a Cultural Revolution-style crackdown on crime.

In announcing Bo's ouster from the Communist Party last month, the official New China News Agency said Bo had "received huge bribes personally and through his family ... and maintained improper sexual relationships with a number of women." He also was accused of helping cover up misdeeds by his wife, who was convicted of murder in the poisoning death of Heywood.

Bo's behavior "badly undermined the reputation of the party and the country, created a very negative impact at home and abroad and significantly damaged the cause of the party and the people," the news agency said.